Process for making inactive menthol



. Patented Sept. 23, 1930 KARL scnoLLxorF, or DUSSELDORF-OBERKASSEL, nn ARTHUR serum, or DUSSEL- DORE-HEERDT, GERMANY, ASSIGNORS 'ro RHErNIscHEiKAMrrER-rABmK, .GESELL- scrum MIT BESCHRANKTEB narrows, or DUSSELDOBF-OBERKASSEL,"GERMANY rnoonssron MAKING ,INAG'DIVE MEBEIHQD H No Drawing. Original application filed June 3Q,:1927, 7eria1'1i1o. 1202,739, and in Germany february '15 1927. Divided and this application filed September 20,1928. Serial No. 307,321.

Thisis a process for the production of inactivelmenthol, new isomer of inactive menthol and making the same, being a divisional applicationof'application Serial No. 202,7 39 filed June th, 1927.

"This process for the production oifinactive menthol, the" racemate of natural menthol consists invsubjecting inactive neomenthol (melting point 51" G.) (acid phthalate'melting point '177 C.) to a transformation through catalysts with hydrogenation catalyzers with heat and in the presenceof hydr genQWith-or Without pressure, by which isomers are produced,- and the mixture of menthol thus produced is treated through refrigeration or fractional distillation thus getting a .fixed inactive menthol which may be purified by themethod describedin U. S. Patent No. 1,'672,346 of June 5,1928.

i The isomerization can be carried out so that inactive neo-menthol can be taken and is subjected to catalysts together with neo-isomenthol. It is possible to treat inactive neomenthol or a mixture of inactive neosmem thol and inactive neo-isomenthol together with inactive isomenthol of a melting point of 53 C. Also one can use neomenthol alone in the mixture with neo-isomenthol' or with isomenthol, melting point 53C., or all three together with thymol, menthone and isomenthone or two of these bodies or all three together being subjected to the influence of hydrogen in the presence of catalyzers. The .isomer-ization of the inactive neomenthol has never hitherto been described. Iii-Patent No. 1,625,771 there isa description of the use of a fluid menthols mixture with hydrogen catalyzers. V

These liquid menthols mixtures have a considerable portion of inactive menthol used as ballast. The treatment'of isolated neomenthol which is kept in a greater quantity with the separation of menthol from the-hydrogenated mass as well as the treatment of neomenthol with the other isomers has the advantage that the isomerization occurs with the theoretical .masses of the material used. That only the isomers are affected by the catalyst is seen. This results in considerable savings in catalysts, in reaction room, heating material etc. Y i

The foregoing process therefore has a considerable advantage over the" former processes. Further according to the foregoing application inactive neomenthol of'any'origin can be subjected to theisomerization process. Useful catalyzers for hydrogenation as well as isomerization are nickel, cobaltecop'per platinum, palladium or mixtures ofthese metals powered form or distributed'oncarriers' such askieselguhr, asbestos, "pumicestone, barium-sulphate and similar materials. 'In place of the metals the oxygencom-' pounds 'orthe easily broken-up organic salts such-gas the 'carbonates and'formates, may be "used. The raw inactivementhol which isobtained according to the preceding can be puri tied for example by converting it intothe ester of the paranitrobenzoic acid, carbonate, box-ate, acid-phthalate or succinate and then the pure crystallized esters or acid esters are wamp-Ze 1 -300 kilograms of inactive neomenthol are treated with 6 kilograms of nickel catalyst, 'at apressure of about 1030 atmospheres of hydrogen at 180 degreescentigra'de withfagitation, until the condition of "equilibrium of the transformation, that is, a

maximum ofinactive menthol, is attained (period "about 24 hours), f The crude inacinactive menthol of melting point 34536 degrees centigrade is obtained. The isomeric menthols resulting from the separation and purification of the inactive menthol are transformed afresh.

Example 2-100 kilograms of inactive neomenthol, admixed with 200 kilograms of thymol or inactive menthone or isomenthone are 'hydrogenatedwith 6 kilograms of ,niclr'el *catalyst at 180 degrees centigrade and under 10-30 atmospheres of hydrogen and at the same time transformed as in Examplel, and

the resulting crude inactive mentholseparated and purified as therein.

' Example 3.A mixture of kilograms of inactive neomenthol, melting point 51 degrees centigrade, 100 kilograms of inactive neo-isomenthol, melting point 12-14 degrees centigrade, 100 kilograms of inactive isomenthol, melting point 53 degrees centigrade, is treated as in Example 1 with 9 kilograms of nickel catalyst at 180 degrees centigrade andunder 10-80 atmospheres of hydrogen, and theresulting crude inactive menthol is separated. and purified astherein.

We claim: a

1. The process for manufacturing inactive menthol, the racemate of natural menthol,

which consists in heating inactive neomenthol with hydrogenating catalysts and hydrogen under agitation and separating from the reaction product the obtained crude inactive menthol. a 1

2. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heating inactive neomenthol with hydrogenating catalysts and hydrogen under pressure and agitation and separating from the reaction product the obtained crude inactive menthol. 1. v 3. The process forv manufacturing-inactive menthol, the racemate of natural menthol, which consists in heating inactive neomenthol admixed with materials which arecapable of being hydrogenated to inactive menthols mixtures with hydrogenatingcatalysts and hydrogen under pressure and agitation and separating from the reaction product the obtained crude inactive menthol.

4. The process for manufacturing inactive menthol, the racemate of natural menthol,

. which consists in heating inactive neomenthol admixed with other isomers of inactive menthol with hydrogenating catalysts and hydrogen under agitation and separatin from the reaction product theobtained cru einactive menthol.

5. The process for manufacturing inactive menthol, the racemate of natural menthol, which consists in heatinginactive neomenthol with hydrogenating catalysts and hydrogen under agitationand separating from the reaction product crude inactivementhol by physical methods. x j a 6. Theprocess for manufacturing inactive menthol, the racemate of natural menthol, which consists in'heating inactive neomenthol .withhydrogenating catalysts and hydrogen under agitation and separating from the reaction product crude inactive menthol by fractional distillation.

7. The process for manufacturing inactive menthol, the racemate of natural menthol,

which consists in heating inactive neomenthol with hydrogenating catalysts and hydrogen under pressure and agitation and separating from the reaction product crude inactive menthol by physical methods. I

8. The process for manufacturing inactiv menthol, the racemate ofnatural menthol,

which consists in heating inactive neomenthol with hydrogenating catalysts and hydrogen under pressure and agitation and separating from the reaction product crude inactive mentholby fractional distillation;

9'. The process for manufacturinginactive menthol. the racemate of natural menthol, whichconsists in heating inactive neomenthol mixed with materials which are: capable of being hydrogenated to inactive menthol mixtures with hydrogenating catalysts and hydrogen under pressure and agitation and separating from the reactlon productcrude menthol with hydrogenating catalysts and hydrogen under agitation and separating fromj the reaction product] crude inactive menthol by physical methods. j I

12. The process for "manufacturing inactive menthol, the racemate of natural menthol, which consists in heating inactive neomenthol mixed with other isomers'of inactive menthol with hydrogenating catalysts and hydrogen under agitation and separating from the reaction product crude inactive menthol by fractional distillation.

' 13 .The process for manufacturing in- -active-menthol, the racemate ofnatural men'- thol, which consists'in heating inactive neomenthol with hydrogenating catalysts and hydrogen under agitation and separating from the reaction product crude inactive {menthol by fractional crystalliz ation.-

- 14:. The process for 'manufacturinginactivemen'thol, the racemat'e of natural menthol, which consists in heating inactive 'neomenthol with hydrogenating catalysts and hydrogen underpressure and agitation and separating from the reaction product crude inactive menthol by fractional crystallization.

. 15. The process for manufacturing" inactive menthol, the racemate of natural menthol, which consists in heating inactive neomenthol mixed with materials which are capable of being hydrogenated to inactive menthol mixtures with hydrogenatingcatalysts and hydrogen under pressureand agitation and separating'from the reaction product crude'inactive mentholby fractional crystallization.

"IOU

16. The process for manufacturing inactive menthol; the racemate of natural menthol; which consists in heating inactive neomenthol mixed with other isomers of inactive menthol with hydrogenating catalysts and hydrogen under agitation and separating from the reaction product crude inactive menthol by fractional crystallization.

v In testimony whereof we afiix our signatures.

KARL SGI-I6LLKOPF. .ARTHUR SERINI. 

